It's important to note that the meaning can be nuanced depending on the context. For example:
* A literal piece of chalk: This could be used to describe an actual piece of chalk, like a teacher might use in a classroom.
* A small, insignificant thing: In some contexts, "el pedazo de tiza" could be used figuratively to refer to something small and unimportant.
To get a more accurate understanding, you'd need to see the sentence it appears in or the context of the conversation.